This section is intended to introduce various aspects of the art, which may be associated with exemplary embodiments of the present techniques. This description is believed to assist in providing a framework to facilitate a better understanding of particular aspects of the present techniques. Accordingly, it should be understood that this section should be read in this light, and not necessarily as admissions of prior art.
Like other modes of transportation that are vital to the U.S. and world economy, pipelines are essential in linking points of production to points of consumption. Pipelines provide an efficient means of transporting crude oil and natural gas from production fields to refineries and processing plants and of distributing petroleum products and natural gas to the consumer. In fact, U.S. pipelines move nearly two-thirds of the petroleum and natural gas products transported annually.
Due to its importance in providing access to crude oil, refined fuel, and other materials, it is of importance that a pipeline undergoes limited integrity failures. Such integrity failures may be facilitated by internal issues such as material defects (e.g., leaks or cracks), outside forces (e.g., destruction by human error), or corrosion.
As one of the primary threats to pipeline integrity, operating experience has shown that inherent corrosiveness of many transported fluids can reduce wall thickness or potentially induce material defects. Currently, the oil and gas industry uses pipeline inspection tools such as in-line-inspection (ILI) tools or pigs to assess the internal condition of a pipeline for corrosion-induced failures. However, many of the current techniques call for accessing pipeline integrity only at periodic intervals for corrosion that has already occurred. Thus, the data provided by the inspection of the pipeline may merely be a lagging indicator of corrosion since any detrimental effects may have already taken place. Furthermore, such sporadic inspections may overlook existing corrosion, thus possibly leading to significant repairs to the pipeline.
Another method of monitoring pipelines for hazardous conditions may include the installation of sensors along the pipeline length. The installation of conventional sensors may provide information at various local points and therefore, may require a large number of sensors to cover the total length of the pipeline. Nevertheless, corrosion mechanisms that affect the integrity of the pipeline, such as microbial induced corrosion, may be localized and not readily detected by point sensors.
U.S. Patent Application Publication 2004/0261547 to Russell et al. discloses a method, an apparatus, and an article of manufacture for detecting a physical condition in a pipeline. The technique includes detecting a physical condition in a pipeline by obtaining vibration data from the pipeline which is representative of the physical condition. The physical condition may be corrosion in the pipeline.
U.S. Patent Application Publication 2012/0099097 to Coupe et al. discloses determining the wall thickness of a structure such as a metallic pressurized pipe. The system includes an optical fiber having a plurality of Fiber Bragg Gratings (FBGs), and a mounting for securing the FBGs over discrete portions of the exterior surface of the pipe such that strain in the pressurized pipe wall is transmitted to the FBGs. The system further includes a light source and a light sensor coupled to an end of the optical fiber. The light sensor converts light reflected back from the FBGs into electrical signals that a digital processor converts into strain measurements. The FBGs are mounted around portions of the pipe expected to have significant metal loss as well as portions of the pipe expected to have negligible metal loss. The method includes comparing relative strains at locations with negligible metal loss to those with significant metal loss to accurately determine the thickness of the wall with metal loss, compensating for temperature effects by considering relative strains at areas of the pipe with and without metal loss, and measuring axial strain on the pipe with one or more of the FBGs to correct for at least one of bending and torsion effects on hoop strain.
U.S. Patent Application Publication 2012/0180552 to Calvo et al. discloses a method and an apparatus using low-frequency guided wave and fiber-optic cables to detect intrusion to a pipeline due to external events. The apparatus includes an acoustic source, a laser light source, a pressure-sensitive optical fiber including a first end and a second end. The second end is connected to the laser light source and oriented toward the acoustic source. The laser light source generates a laser pulse traveling through the pressure-sensitive optical fiber toward the acoustic source. The laser pulse includes a time-of-flight. The acoustic source generates an acoustic wave. The acoustic wave includes a plurality of evanescent wave fronts. The plurality of evanescent wave fronts, upon scattering from a non-uniform material region, radially contracts the pressure-sensitive optical fiber to alter the time-of-flight of the laser pulse along the pressure-sensitive optical fiber by increasing the fiber length.
U.S. Pat. No. 8,131,121 to Huffman discloses a fiber surveillance system for monitoring a pipeline. The surveillance system includes an optical fiber acoustically coupled to the pipeline to detect acoustic signals associated with vibrations or other activity near or from the pipeline. Optical energy is injected into the optical fiber and an optical detector receives an optical return-signal having certain characteristics resulting from vibrations impinging on the optical fiber. An analyzer is configured to determine operating information about the pipeline based on the optical return-signal. Two or more fibers can be acoustically coupled to the pipeline and arranged in varying configurations to yield greater resolution.
There are several existing technologies that may facilitate the monitoring of a pipeline for intrusions, including the use of acoustic or fiber-optic techniques. However, in the pipeline transportation industry, advances in pipeline monitoring (of intrusions) and mechanical integrity with and over existing technologies can result in significant economic benefit. Indeed, there is an ongoing need for the continuous improvement of monitoring of pipeline integrity and in promoting pipeline performance.